Thymectomy in non thymomatous myasthenia gravis: Impact of pathology on outcome and role of survivin in pathogenesis

摘要

Background Myasthenia gravis is an autoimmune disorder characterized by production of acetylcholine receptor antibodies. These antibodies are mainly produced by thymic B-lymphocytes. Our aim was to detect the correlation between thymic pathology and outcome of myasthenia gravis. Moreover, we tried to detect the involvement of survivin as an apoptosis inhibitor in pathogenesis of myasthenia. Methods This study was a prospective study conducted on 36 non thymomatous myasthenic patients subjected to thymectomy. Patients were followed for 6 months after operation. Moreover, 36 control normal thymic specimens were obtained from patients operated for open heart surgery. Resected thymic tissue was sent for histopathological examination and immunohistochemical staining by survivin to examine its role in pathogenesis of myasthenia. Results Patients were divided into group A with hyperplastic thymus and group B with atrophic thymus. Nine patients had no improvement after surgery and the remaining had variable degrees of clinical improvement. Pathology of thymus did not affect clinical outcome with significant improvement in both groups. Decreased duration of symptoms before surgery and female sex are statistically associated with more improvement of patients' symptoms. Positive expression of survivin was detected in germinal centers of all hyperplastic and atrophic thymuses. All the control thymuses were negative for survivin expression. Conclusion Thymectomy for myasthenia gravis is an effective and beneficial procedure even in patients with atrophic thymus. Survivin is expressed in all myasthenic thymuses confirming its role in pathogenesis of myasthenia gravis.